Draft regulators



April 30, 1963 M. w. PATRICK QRAFT REGULATORS Filed July 24, 1959 INVENTOR Mam/1 fine/M.

3,087,677 DRAFT REGULATORS Malcolm W. Patrick, Redford, Ohio, assignor to Hupp Corporation, Cleveland, Ohio, a corporation of Virginia Filed July 24, 1959, Ser. No. 829,364 3 Claims. (Cl. 236- 45) This invention relates to draft regulators and more particularly to such regulators which are positioned in the flue between a combustion device and chimney for controlling the admission of air into the flue to stabilize the draft through the flue.

As is well known in the art, the draft from a combustion device such as a gas or oil burner in a domestic heating system should be maintained at a constant level for eflicient, safe operation. Heretofore it has been proposed to provide a controlled opening in the flue usually adjacent the chimney to permit atmospheric air to be drawn into the flue when the draft in the chimney becomes excessive.

A regulator of this type which is disclosed and claimed in United States Patent 2,721,705 comprises generally a counterweighted regulator vane which is inserted into the end of the horizontal flue pipe of a conventional oil furnace. The vane is normally held in closed position by the counterweight and is moved away from closed position automatically by the differential pressure existing across the vane when the chimney draft becomes excessive. The counterweight is manually adjustable to render the resistance offered by the regulator vane to the pull of the chimney draft substantially uniform throughout the range of movement of the regulator to thus maintain the draft throughout the combustion apparatus as nearly constant as possible.

While this device provides adequate protection for the combustion unit, nevertheless it does decrease the overall efliciency of the system to some extent since the regulator vane may remain open even during intervals during which combustion is not taking place thus drawing heated air out of the furnace room through the chimney which draws outside air into the furnace room with a substantial loss of heat in the heating system and its environment.

Another undesirable condition arises when a combustion cycle is initiated. During this period the vane often oscillates during the stabilization period which leads to the production of objectionable quantities of smoke and inefiicient combustion and sometimes produces objectionable noises in the system. With the foregoing considerations in mind, it is the principal purpose and object of the present invention to provide improved draft regulators which eliminate the above mentioned disadvantages of all prior known systems and provide increased flame stability and combustion efficiency and substantially reduce the noise level in the system.

It is also an object of the present invention to provide improved draft regulators which are automatic in operation and which are automatically held in closed position whenever the gases in the line are below a certain temperature, i.e. when the combustion apparatus is not operating or during the interval after the initiation of the combustion cycle and before the flue has reached operating temperature.

It is also an object of the present invention to provide improved draft regulators which are simple yet effective in operation, which comprise a minimum number of operating parts and which may be readily installed in existing systems as well as in new equipment.

In accordance with the present invention, these and other objects are accomplished by the provision of a novel thermostatically controlled draft regulator unit 3,687577 Patented Apr. 30, 1963 ice which is automatically held in closed position except when the combustion device is operating and the working temperature has reached a predetermined value.

During the interval between the initiation of combus- {tion and the time when combustion apparatus reaches full operating temperature, efficient combustion can be achieved only if the combustion air is supplied in amounts substantially in excess of that normally required when the normal operating temperature has been reached. Heretofore there has been no provision for the supply of excess air for the starting cycle.

In accordance with the present invention, the thermostatic control element maintains the draft regulator closed during the starting operation. Thus all of the draft produced by the chimney must be directed through the burner thus effectively providing increased air flow to assure combustion efiiciency during starting.

Additional objects and advantages of the present invention will become apparent as the description proceeds in connection with the accompanying drawings in which:

FIGURE 1 is a side elevation of a portion of the flue system in which the draft regulator of the present invention is installed;

FIGURE 2 is an enlarged end elevation of the portion of the apparatus shown in FIGURE 1 looking in the direction of the arows 2-2 of FIGURE 1;

FIGURE 3 is a vertical section taken along line 3-3 of FIGURE 2;

FIGURE 4 is an enlarged elevation of the thermostatic element of this system removed from the remainder of the structure, the view being taken in the direction of arrows 4-4 of FIGURE 3;

FIGURE 5 is an end elevation of the thermostatic unit of FIGURE 4; and

FIGURE 6 is an enlargement of a portion of FIGURE 3 showing details of construction.

Referring now more particularly to the drawings, the draft regulator assembly indicated generally at 10 is installed in the horizontal portion 12 of a T-fitting 14, the opposite end of the portion 12 being connected to the flue pipe 16 of a furnace 18. The vertical portion 20 of the T-fitting is connected through suitable conduits 22 and 24 to a chimney (not shown).

The draft regulator assembly of the present invention is a unitary sub-assembly which may be easily installed or removed from the open end of the pipe section 12. The sub-assembly 10 includes a main frame member 26 which is provided with a cylindrical portion 28- received with a sliding fit in the open end of the member 12. The frame member 26 is also provided with an annular lip 30 which limits inward movement of the frame member into the open end of the pipe 12. Projecting radially inwardly from the inner end of the cylindrical portion 28 is a radial wall 32, the inner edge of which defines an opening 34 which is circular except for a horizontal chordal section 36. Extending substantially parallel with the chordal section 36 is a slot 38 which is of greater depth at its midpoint than at its opposite ends for a purpose to appear.

The vane member 40 is an essentially circular sheet metal stamping of slightly smaller diameter than the opening 34 in the frame member 26. The vane member 40 is provided with an annular head 42 for stiffening purposes. Welded or otherwise secured to the inner surface of the vane 4t) is a downwardly projecting leg 44 of a pivot member which is provided with a sharp reverse bond as at 46 which is then smoothly again reversely bent to extend outwardly of the frame member 26 and which terminates in a horizontal portion 48. The opposite edges of the reversely bent portion 46 of the pivot arm are suspended on the lower edge portions of the slot 38 for free swinging movement.

Adjustably secured to the horizontal portion 48 of the arm assembly is a counterweight 50 which is held in place by a carriage bolt 52 which extends through an elongated slot provided in the portion 48 of the arm. Because of the elongated slot, the position of the counterweight may be adjusted as desired to adjust the degree of differential pressure across the vane 40 necessary to move the vane away from its fully closed position. Further details of the mechanism thus far described may be had by reference to the aforesaid US. Patent 2,721,705.

An important feature of the present invention to which detailed reference will now be made is a thermostatic assembly indicated generally at 54 which modifies the pressure-gravity actuation of the vane 40. The assembly 54 comprises a stamped one-piece sheet metal bracket 56 which is provided at one end with flanges '58 and 60 attached by screws 62 and 64 to the radial flange 32 adjacent the opposite ends of the slot 38. The bracket 54 is provided with integral cross pieces 66 and 63 and to the former is welded an offset portion 70 of a bi-metallic strip 72. The main operating portion 74 of the strip 72 is connected to the attachment portion 70 by a vertical section 76. When the thermostatic assembly 54- is removed from the assembly shown in FIGURE 3 and the unit is cold, the free end of the strip portion 74 bends downwardly into contact with the cross-piece 68 and as the temperature rises, the strip portion 74 moves upwardly from this limit position. When the unit is installed as shown in FIGURE 3, the free end of the strip portion 74 bears against a lug 78 struck from the portion 44 of the vane pivot arm.

The parts are so dimensioned that the free end of the bi-metallic strip 74 exerts a substantial pressure on the lug 78 which is effective in a direction to close the vane 40 when the furnace is not in operation, for example in an ambient temperature of 75 degrees. Upon a rise in temperature occasioned by operation of the combustion device the closing force exerted by the bi-metallic strip is gradually removed. Accordingly, when the furnace or other combustion device is not in operation, ambient temperature prevails in the flue and the vane 40 is held in closed position both by the action of the counterweight 50 and by the bi-metallic control assembly 54. The operation of the bi-metallic unit '54 effectively prevents the passage of ambient air out through the chimney and eliminates the possibility of any noise occasioned by scillation of the vane 40 under these conditions.

During the starting cycle of the combustion apparatus the vane is also held in closed position thus assuring that all of the air passing out through the flue first passes into the combustion chamber assuring a stable non-smoking and efiicient flame during the critical starting cycle. Subsequently as the temperature of the flue progressively increases, the free end of the bi-metallic strip moves upwardly decreasing the closing pressure exerted on the lug 78 and finally at a predetermined elevated temperature the bi-metallic strip exerts no pressure on the lug 78.

It is to be noted that the decrease in the force exerted by the free end of the bi-metallic strip is gradual so that the amount of air admitted through the draft regulator will gradually increase in accordance with the combustion conditions to create rapid stabilization of the flame and to maintain the flame in a stabilized condition. Sooting, due to poor combustion generally prevalent under extreme weather conditions at the combustion start is minimized and excessive outside air infiltration into the furnace room which was previously unavoidable when the furnace was out of operation are eliminated with the consequent improvement in the overall heating efliciency of the systern.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiment is therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by United States Letters Patent is:

1. A draft regulator for a furnace flue comprising a vane adapted to be pivotally mounted in a flue for swinging movement between open and closed positions, said vane being gravity-urged toward closed position and being movable toward open position by air pressure differentials, a bi-metallic element, and means for cantilever mounting one end of said bi-metallic element within a flue, said bi-metallic element adapted to be exposed to the gases in a flue, said bi-metallic element having an opposite free end directly engageable with said vane to urge said vane toward closed position when the temperature of the gases within said flue is low, said opposite free end of said bi-metallic element being moved out of pressure contact with said vane upon an increase in the temperature of the gases within said flue to permit said vane to move toward and away from said closed position independently of said bi-mctallic element.

2. A draft regulator for a furnace flue comprising a vane adapted to be pivotally mounted in a flue for swinging movement between open and closed positions, a counter-weight rigid with said vane for opposing initial movement of said vane away from said opening, an elongated bracket, means for mounting said bracket within a flue, said bracket extending away from said vane and adapted to extend into a flue, and a flexible bi-metallic element cantilever mounted at one end on the end of said bracket remote from said vane, said bi-metallic element adapted to be exposed to the gases within a flue, said bi-rnetallic element having an opposite free end engageable with said vane to urge said vane toward closed position when the temperature of the gases within said flue is low and said free end of said bi-metallic element being moved out of pressure contact with said vane upon an increase in the temperature of the gases within said flue to permit said vane to move toward and away from said closed posit-ion independently of said bi-metallic element.

3. A draft regulator for a furnace flue comprising a frame adapted to fit within a flue, said frame having a central opening, a vane pivotally mounted on said frame for movement toward and away from. said opening, a counter-weight rigid with said vane for opposing movement of said vane away from said opening, an elongated bracket attached to and extending away from said frame inwardly thereof, a flexible bi-metallic strip cantilever mounted at one'end on to the end of said bracket remote from said frame, said element being adapted to be exposed to the gases within a flue, said bi-metallic element having an opposite free end directly engageable with said vane to urge said Vane toward said opening when the temperature of the gases Within a flue is low, said free end of said bi-metallic element being moved out of pressure contact with said vane upon an increase in the temperature of the gases within a flue to permit said vane to move toward and away from said opening independently of said be-metallic element.

References Cited in the file of this patent UNITED STATES PATENTS 1,958,847 Cunningham May 15, 1934 2,167,307 Monney July 25, 1939 2,212,976 Brace Aug. 27, 1940 2,264,590 Sabins Dec. 2, 1941 2,721,705 Patrick Oct. 25, 1955 FOREIGN PATENTS 1,130,105 France June 4, 1955 

1. A DRAFT REGULATOR FOR A FURNACE FLUE COMPRISING A VANE ADAPTED TO BE PIVOTALLY MOUNTED IN A FLUE FOR SWINGING MOVEMENT BETWEEN OPEN AND CLOSED POSITIONS, SAID VANE BEING GRAVITY-URGED TOWARD CLOSED POSITION AND BEING MOVABLE TOWARD OPEN POSITION BY AIR PRESSURE DIFFERENTIALS, A BI-METALLIC ELEMENT, AND MEANS FOR CANTILEVER MOUNTING ONE END OF SAID BI-METALLIC ELEMENT WITHIN A FLUE, SAID BI-METALLIC ELEMENT ADAPTED TO BE EXPOSED TO THE GASES IN A FLUE, SAID BI-METALLIC ELEMENT HAVING AN OPPOSITE FREE END DIRECTLY ENGAGEABLE WITH SAID VANE TO URGE SAID VANE TOWARD CLOSED POSITION WHEN THE TEMPERATURE OF THE GASES WITHIN SAID FLUE IS LOW, SAID OPPOSITE FREE END OF SAID BI-METALLIC ELEMENT BEING MOVED OUT OF PRESSURE CONTACT WITH SAID VANE UPON AN INCREASE IN THE TEMPERATURE OF THE GASES WITHIN SAID FLUE TO PERMIT SAID VANE TO MOVE TOWARD AND AWAY FROM SAID CLOSED POSITION INDEPENDENTLY OF SAID BI-METALLIC ELEMENT. 